Burner control



R. w. JOHNSON 2,378,483

BURNER CONTROL June; 1K9, 1945.

Filed Aug. l2, 1940 5 Sheets-Sheet l Mofo/e j 63 so a5 es 47 @lz 76 Q2 y /24 w' O' A a INVENTOR TTORNEY.

June 19, 1945'.

ow V0.4 7,465

Elf/30 5/ R. W. JOHNSON I l BURNER CONTROL Filed Aug. 12, 1940 5 Sheets-Sheet 2 fg o 60 y INVENTOR )POV n( .MHA/.50N

MXL

A TTORN EV.

June 19, 1945. R. w. JOHNSON BURNER CONTROL Filed Aug. 12, 1940 3 Sheets-Sheet 3 INVENTOR Row 1M Jo/(A/.SOA/

A TTO R N E Y.

Patented June 19, 1945 UNITEDA STATES lPim-:NT OFFICE BUnNEacoN'rnoL -Boy W. Johnson. Milwaukee. Wis.

muessen am 12, 1940, semi No. 352,251

12 Claims.

This invention relates to an improvement in n control mechanism especially designed and adaptv hot air furnace or heater employing a pot type burner. or its equivalent, to which oil or liquid fuel is fed by gravity under control of a metering valve embodied in a constant level oil control device. Air to support combustion is supplied to the combustion chamber usually by means of an electric motor-driven fan.

One of the objects of the invention is to provide a control mechanism of this character, which effectively coordinates the action of the metering valve and of the air supply means so that when the metering valve is fully opened to provide for a high or maximum ilre in the burner, air in adequate quantities to support such combustion will be delivered to the fire pot of the burner, whereas when the metering valve is adjusted to cut down the supply of fuel, and lower the llame or re in the burner, the supply of ai-r will be correspondingly reduced. These advantages obtain irrespective of whether the device is'manually or thermostaticallycontrolled. e

Another object of the invention is to provide a control device of this character, which may be readily converted from manual to thermostatic control, that is from a structure wherein the control over the metering valve and the interlocked air supply means is regulated by a manually ad- .iustable control knob to one wherein the control over the air andv fuelsupply is effected by means of a room thermostat, and the arrangement is such that the control exercised by the manually adjustable control knob is available to supple-v ment or renne the control exercised by the room thermostat when the latteris also employed.

Another object of the invention is to provide a control device of this character which automatically shuts on the electric motor driving the fan which supplies the forced draft to the burner when the metering valve is fully closed, and which also automatically brings about movement of the 45 metering valve to pilot or low fire position in the event of current failure.

Another object of the invention is to provide a control device having these advantages and capacities, and which is extremely simple, compact and closely organized in construction; reliable, safe and economical in operation, and easy and comparatively inexpensive to manufactureand install. l

Other objects and advantages reside in certain novel features of theconstructiomarrangement, and combination of parts, which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which:

Figure 1 is a view in top plan, with the cover plate removed, of an oil and air control mech anism embodying the present invention and of the type which is manually controlled;

Figure 2 is a view in vertical cross section taken on line 2-2 of Figure 1 but showing only the control unit, parts being shown in elevation for the sake of simplicity in illustration;

Figure 3 is a fragmentary view in vertical cross section taken on line 3-3 of Figure-1, parts being again shown in elevation for the sake of illustration;

Figure 4 is a fragmentary view in top plan showing a portion of the cover plate which surrounds the manually adjustable control knob;

Figure 5 is a view similar to Figure 1 but showing the device when converted to a thermostatif cally controlled unit;

'Figure 6 is a fragmentary view in vertical cross section taken on line 6--6 of Figure 5;

Figure 7 is a fragmentary view in vertical cross section taken through the control knob and metering valve and associated elements, parts being shown in elevation for the sake of simplicity in illustration;

Figure 8 is a plan view showing how the oil control device is combined with the damper embodied in the conduit between the motor-drivenv fan and the combustion space of the burner;

Figure 9 is a view in end elevation of the construction shown in Figure 8; and

Figures l0 and. 11 are fragmentary sectional views taken on lines Ill-I0 and |l|l, respectively of Figure 1.

Referring to the drawings, it will be seen that in both forms of the invention, the control mechanism comprises a main casing, designated generally at I0, and having a main liquid supply chamber Il therein (see Figures 6 and 7). Liquid fuel is supplied through an inlet I 2, equipped with a strainer I3, to an inlet valve I4 controlled in its action by a main float I5 so that a constant level of liquid fuel is maintained in the supply chamber Il. A safety shut-off mechanism, designated generally at' I6, is combined with the means for maintaining the level of' liquid fuel in the main supply chamber il, in the manner fully described and claimed in my Patent 2,068,138, granted Jannary 19, 1937, and Patent 2,120,364, granted June t a lateral opening or port I9 which provides forv communication between the interior of the guide and the liquid supply chamber II. Just below this port the tubular valve guide has an internal valve seat 20. A metering valve 2| is slidably fitted in the tubular valve guide for vertical movement, and has its lower end reduced and slotted and designed to coact with the valve seat and with the internally restricted lower end of the valve guide I8 to meter the flow of oil from the liquid supply chamber to the outlet passage I1. The metering valve 2| also has a beveled portion 22 which snugly engages the beveled valve seat 20 in the fully closed position of the valve so as to completely shut off flow of fuel in such positions. The metering valve 2| is constrained to vertical sliding movement and is held against rotation by means of a transverse guide pin 23 which extends through a diametric opening provided therefor in the metering valve and projects at its ends through and laterally beyond diametrically opposite vertical slots 24 provided in the upper portion of the tubular valve guide I8.

Means is provided for biasing the metering valve to open position and may conveniently take the form of an expansible coil spring 25 having its lower end engaging an abutment 26 and its upper end engaging the under sides of the projecting endsof the guide pin 23.

The control device proper is applied to the top of the main casing I Il and comprises a control casing 21 which includes a floor or bottom wall 23 having integral therewith an upstanding peripheral wall 29 and a depending vertical flange 30 rabbeted around its lower edge to interflt with the upper edge of the peripheral wall of the main casing Ill. The control casing is completed by means of a removable cover plate 3| releasably secured in position by a suitable number of screws 32. Screws 32' releasably secure the control casing 21 to the main casing I0.

'I'he portion of the floor 28 on the control casing which immediately overlies the metering valve end of the body portion of the knob 35 by means of a combined abutment and driving plate 38 and screw-threaded stud 39. The details of the construction of this variable throw cam per se form no part of the present invention and are fully disclosed and claimed in U. S. Patent No. 2,244,161, issued June 3, 1941, to Roy W. Johnson. `Below its head the stud 33 is provided with a collar 40 which slides in the upper end of the guide I8.

The lower end of the stud 39 bears against a boss 2|' formed at the upper end of the metering valve 2|. The active face of the cam 31 rides on an abutment lug 4I which may be integrally formed with an adjustable supporting arm 42. The cam is pressed down against the abutment lug by means of a coil spring 43 which encircles the body portion of the knob, abuts the inturned upper edge 33 of the flange 33 at its upper end, and bears down on the combined abutment and driving plate 38 at its lower end.

The supporting arm 42 is constituted of stiiy resilient metal. One end of the arm 42 is fixedly supported on the control casing 21 by means of a rivet 44. The opposite end of the arm is formed with a threaded bearing 45, and an adjusting screw 4E is interthreaded with the bearing 45 and at itsA upper end has a swivel support in a socket 41 provided therefor in the oor of the control casing. This socket is open at its upper end and the upper end of the screw is crossslotted to facilitate the turning of the screw and consequent flexure and adjustment of the arm and its abutment. The adjustment -thus provided controlsA the high and low fire positions of the metering valve under the influence of the manually adjustable cam 31.

In order to adapt a manually controlled device of this character to thermostatic control, it is proposed to equip all units at the factory with an auxiliary valve operating mechanism responsive to the control of a room thermostat or other thermo-responsive control means. This auxillary valve-operating mechanism comprises a valve-operating lever, designated generally at 5t, and having one end pivotally mounted or fulcrumed as at 5| `on the underside of the casing of the control unit. An arm 52 of the'lever is engageable with the guide pin 23 of the metering valve to control the position of the metering valve. The valve-operating lever 50 also has a second lever arm 53, which may be integral therewith and which is preferably horizontally disposed. In fact, as shown in the drawings, the valve-operating lever 50 may be constituted of a sheet metal stamping. The outer ,end of the arm 53 of the lever 50 engages the lower headed end of an operating pin 54 which is slidably fitted in a bearing 55 integrally formed with the oor of the casing of the control unit. In order to control the high and low fire positions of the valve when it is thermostatically controlled, high and low lire stops for the lever 50 are provided, the high fire stop being in the form of an adjustable screw 56 carried by the iloor of the casing of the control unit and engageable with the arm 53 of the lever to limit the upward swing thereof and consequently limit the extent to which the metering valve may move away from its seat. The low fire stop may comprise an adjustable screw 51 threadedly interconnected with the arm 53 of the lever 50 and engageable with the supporting arm 42 to limit the downward swinging movement of the valve-operating lever 50 and consequently the extent to which the 1ever may move the valve toward its seat.

An electro-responsive power element is provided in the casing of the control unit for controlling the position of the valve-operating lever 5|), this power element exerting its control on the valve-operating lever through the sliding pin 54. Preferably the electro-responsive power element comprises generally a bimetallic leaf 60 having one end flxedly supported as at BI on a terminal board 62 supported within the casing of the conasva-ies' supporting posts 83 and screw 04. -An extension 8l, ilxed to the free end of the bimetalllc leaf, bears on the upper end of the sliding pin Il in both forms oi the invention. An electric heating element 68, encased in mica or other electric insulating material, is supported on the bimetallic leaf in heat lnterchanging relationship thereto, rivets 81 or the like coacting with its mica. casing to secure the electric heating element in position on the bimetallic leaf. The manner in which the energization and deenergization of the electric heating element 66 is controlled and each embodiment of the invention will be hereinafter described.

Referring now to Figures 8 and 9, the numeral 'it designates an electric motor which drives a fan or blower li. The blast of air from the blower is discharged into a conduit 52, which is coupled up to the burner (not shown). The conduit 'i2 may be carried in part at least by a bracket'ld fastened to the main casing i0. An opening l is provided in the portion of the conduit 12 adjacent the casing i0. A damper l is provided for the opening it and is ixed to a shaft 'i6 supported for rotationin bearings l1. A weight i8 y fixed to the damper i5 on one side ofthe shaft it biases the damper to a position to close the opening le. By virtue of its mounting, the damper l5 may be positioned to close the opening i4 or to partially or fully open it, and incombustion in or scavenging of the ilre pot, the interconnection between the knob and the damper lever 82 is of the special nature now to be described. Underlying the damper-operating lever is an actuating lever 9|, which is curved in substantially the same manner as the section 85 of the lever 82, and which has its inner or mounting end widened to a less degree than the widened attaching end oi the lever'BZ, so much so that the widened inner end of the lever 9| is accommodated between one of the lugs 81 and an intermediate bearing lug 8l' integral with and depending from the mounting portion 86 of lever 82 and providing an additional bearing for the pin 88 to better adapt the latter to pivotally support the actuating lever 9|. The widened inner end of the lever 9| also has upwardly. extending mounting lugs Q2 which also have alined pivot openings through which the pivot pin t9 passes to provide a fulcrurn for the actuating lever. The driving connection between the knob 3E and the actuating lever 9| is provided by a driving pin e3 nxed in the actuating lever and projecting laterally therefrom so that one end of the pin underlies and is engaged. by the lower edge of theA skirt 36 of the knob 35. The biasing action of v the weight i8 of the damper 'i5 is sumciently cidentally, also, when moving away from a position in which the opening 'ld is closed to a position in which it is partially or fully operi,A the damper l5 is eective to block in varying degrees the passage through the conduit l2 from the fan to theburner. One end of the shaft 'i5 projects vbeyond. the bearing il and to this projecting portion of the shaft 'l5 a crank arm 'i9 is secured. A

crank pin d@ is xed to the outer end of the crank .the form of the invention shown in Figures 5 p and 6. While the damper-operating levers 92 and 93 have one primary function in common, they diiler somewhat in construction, and also in their manner of operation, in the two forms 'of the invention, and hence have been given different referencel characters.

L Referring nowV to Figures 1 and 2 it will be seen that the damper-operating lever 82 is disposed transversely of the control unit adjacent the end thereof at which the manually operable knob 35 is located. The damper-operating lever 82 hasv a straight section 84 with which is integrally formed a curved section 85, the latter extending around the knob 35 and merging into a widened attaching or mounting portion 86, the ends of which are formed with depending lugs 81 (see Fig. 10) having aligned pivot openings which receive the pivot or fulcrum pin 88. 'I'his pin is supported on notched seatsv 89 and is held in position by screws 90 threaded into the control casing and having their heads overlapping and holding the fulcrum pin against its notched seats.

In this for-m of the invention the pOSition of the damper-'operating lever 82 is regulated by the adjustment of the knob 35, but inorder that the supply of air from the fan to the combustion er the metering valve is closed to insure complete strong to swing the lever 82 upwardly and cause its driving pin e3 always to engage the lower edge of the skirt 36.

A yieldable interconnection, accommodated in gaged with the lever 9| and its lower end engaged with a nut or collar 96 adjustably mounted on the lower end` portion of the screw 9d. This yieldable connection tends to cause the damper-operating lever 82 to move with the actuating lever 9|, but permits the motion of the lever 82 to lag behind that of the actuating lever 9| under the influence of a. dash-pot, designated generally at 91, in certain phases of the operation. y

The dash-pot 97 (see Fig. 3) comprises a cylinder Qa having its upper open end' formed with an ontwardly directed marginal iiange, the flanged upper end of the dash-pot abutting a seat provided therefor on the under side of the door of the casing of the control unit. Screws 99 are threaded into the floor of the control unit and have their edges engaged with the ilanged upper lend of the cylinder 98 of the dash-pot to rmly secure the cylinder 98 in position. The lower end of the cylinder 98 is provided with an end wall |00 having a central port |0I. A disk valve |02 cooperates with the ported end wall at the lower end of the casing 98 and is limited in its movement away from its end wall |00 by means of an internal shoulder |03 formed on the cylinder 98.' A piston |04 is slidably iltted in th'e lower portion of the cylinder 98 which is machined to provide the working chamber of the cylinder. Integral with the piston proper is the tapered extension or stem |05 which is disposed in the portion of the cylinder `98 above the working chamber thereof. A spring |06 encircles the stem |05 oi the piston, the spring, atits lower end. bearing on an upwardly facing internal shoulder |01 provided on the cylinder 98 at the upper extremity of its working chamber and having its upper end engaging a collar |08 suitably seoured'to the upper end of the stem of the piston. The spring is under compression and biases the piston |04 to its uppermost position. The stem |06 and piston |04 are formed with an axial opening terminating short of the lower end of the piston but extending out through the upper end of the stem. A portion of a piston rod |09 is accommodated in this axial opening of the piston. The piston rod '|09 has pointed ends, one engaging the tapered formation at the lower end of the axial opening in the pistong|04 and the other engaging a tapered recess ||0 provided on the under side of the lever 82. When the knob 85 is turned to move the metering valve 2| to fully shut-off position, its skirt 34 moves downwardly as far`as it may, and'in so doing it presses down on the pin 93 thereby swinging the actuating le ver 9| downwardly. This downward motion of the actuating lever tends to cause the lever 82 to swing downwardly with it, but such motion of the leverv 82 is resisted by the dash-pot 91, and this with such force that the spring 95 of the yieldable connection between the levers first yields. As the force built up in the spring 85 increases, it gradually becomes sufficient to cause the lever 82, to which it is applied, to move the piston |04 of the dash-pot 91 downwardly, the fit of the piston |04 in the working chamber permitting appropriate leakage between its outer wall and the inner wall of the working chamber of the cylinder 98, the disc valve |02, of course, being closed at the time. Thus, before the damper is moved to full open position, and before the motor switch for the fan is opened in a manner to be hereinafter described, the metering valve 2| is fully closed.

The present invention proposes to incorporate in the circuit for the motor 10 a switch, designated generally at and which is so constituted and so organized with the other elements of the unit that it will automatically close when the metering valve is at No. 1 or higher position, but will be automatically opened by the damper-operating lever 82 shortly after the metering valve has been brought to fully closed or shut-off position. Furthermore, in the same motor circuit the electric heating element 66 for the bimetallic leaf is incorporated so that in the event of current failure, and consequent cessation of the air supply under the influence of the fan 1|, the metering valve 2| will automatically be brought to its low or pilot fire position.

For these purposes one side of the line, designated at H2, is connected to binding post ||3 mounted on the terminal board 62 and directly connected to the attaching portion ||4' of the movable contact I4 of the switchi I. This movable contact ||4 is in the form of a blade spring, one end of which is fixed to the binding post |I3, as described, and the main portion of which is offset downwardly from the binding post and the underside of the terminal board. The outer extremity of the blade contact ||4 is doubled back upon itself, as at ||5, and carries a contact button ||5 which is engageable with the fixed contact |I6 of the switch. The fixed contact ||6 of the switch is connected by a exible and insulated conductor or wire ||1 to one terminal of the electric heating element 66. The other terminal of this electric heating element 66 is connected by conductor to one terminal of the motorI 10. The other motor terminal is connected by a conductor |2| to a binding post |22, also mounted on the terminal board 62 and connected by wire |23 to the other side of the line.

The switch is constituted to open and close with a snap action by virtue of the provision of a U-shaped permanent magnet |24, which is carried on 9, bracket |24 provided therefor, The bracket |24 is mounted on the terminal board 62 and also provides a support for an adjusting screw I6' for the fixed contact ||6. The magnet |24 has its poles projecting through an opening provided therefor in the terminal boardA 62 and straddles4 the fixed contact ||6 in such fashion that when the contact button H5 is proximate to or engaged with its fixed contact ||6 it is located in the field of the magnet |24.

In order to provide for the control of the switch .from the damper-operating lever 82, this lever is provided with an extension or enlargement |26 having an internally threaded opening therein. A screw |21 is threadedly engaged with this opening and projects below the lever. A strip of insulating material, designated at |28, has one end riveted or otherwise suitably fastened to the body portion of the movable contact ||4 and has its outer end underlying and engageable with the ,lower end of the screw |21. With this construction, when the knob 35 is adjusted to move the metering valve to shut-off or fully closed position, the actuating lever 9| is moved down as far as it may be, and acting through its yieldable connection, and against the action of the dash-pot 91, eventually also moves the damper-operating lever 82 downwardly as far as it may be. As the damper-operating lever 82 approaches the lower limits of its downward swing, the screw |26 strikes the strip |28 and pulls the body of the movable contact ||4 downwardly, There is first a certain amount of fiexure between the body portion of the movable contact ||4 and its double-backed end ||5 until suicient spring energy is stored up to cause the movable contact button H5 to pull away from the iixed contact ||6 with a snap action, the spring tension 4built up having at such time reached a value which is sufficient to overcome the influence of the field of the permanent magnet |24.

When the knob 35 is turned to No. 1 position, or to any position thereabove, then the screw |21 moves up out of engagement with the strip |28, and the switch closes with a snap action under the influence of the inherent tensioning of its movable contact blade I|4 and of the permanent magnet |24.

In the form of the invention shown in Figs. l and 2, the heating of the bimetal 65, following the closure of switch causes the arm 52 to engage the pin 23 (see Fig. 7) and thus opens the valve to high fire position. Upon closure of the current, the valve will return to the low re position determined by the setting of the knob 35.

In the form of the invention -shown in Figures 5 and 6, the supply df current to the electric heatingv element 66 is under the control of a room thermostat |30. The fan motor 10 runs continuously and the regulation of the air supply is effected by the damper 16. A screw |3| is mounted on the lever 83 and is releasably held in any adjustment by locking plate 32. The screw depends below the lever 83 and is engageable with the upper surface of the outer end of the strip-like extension 65 of the bimetallic leaf 60. As the high fire position of the metering valve 2| is controlled solely by the bimetallic leaf 60. and as such a lea! 80 warps slowly upon the deenergization of Y its heating element 88, there is no necessity for.

^ makin; provision for an'overrun by theV fan 1I,

The constructions described make readily available either a manually or thermostatically controlled unit which exercisesthe desired regulation over both the oil and air supply. The units, as -to their means for maintaining aconstantlevelas to the metering valve construction, and as to the auxiliary lever mechanism for operating the metering valve thermostatically, are identical. In both instances the same `terminal board is provided and carries a bimetallic leaf and its heating element. 'll'he levers 82 and 88 may be interchangeably employed, and when the lever 83 is employed and the device thermostatically controlled, the actuating lever 9|, dash-pot 91, and switch IH may be readily omitted.

Irrespective of whether the device is manually or thermostatically controlled, the bimetallic leaf renders the control mechanism fail-safe. In the event of current failure in either instance, the

metering valve is-automatically moved to low or.

pilot fire position. Then, again. when the device is thermostatically controlled, the manually adjustable control knob provides for additional regulationW of the low fire position.

While I have shown and described several constructions in which the invention may be advantageously embodied, it is to be understood that the constructions shownthave been selected merenly for the purpose of illustration or example, and that various changes in the size, shape, and arrangement of the parts may be made without'departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. A control mechanism for use in regulating the supply of oil and air to an oil burner and comprising a casingJ having a liquid supply chamber provided with an outlet, a metering valve`for regulating flow through said loutlet, manually adjustable cam means cooperable witnthe valve to shift the same from open to closed position and vice versa and there y vary the amount of fuel supplied to the burner, afan for supplying air t the-burner, a conduit between t fan and burner, a damper in said conduit, a amper-operating lever connected to the damper, an actuating lever having driving connection with and controlled by the adjustable cam means, a yieldable driving connectionV between the jactuating lever and the damper-operating lever, and a dash pot coacting with the damper-operating lever to constrain the same to lag .behindA the actuating' lever upon transmission `oi vopening movement to the damper.

2. In a'controi mechanism forregulating the supply of oil and air to a burner, a casing providing an oilsupply chamber, a metering valve biased toward open position-and controlling the iiow of oil from the chamber, manually'adj stable means ilimiting the degree of opening of he valve, a fan for supplying air to the burner, a

and opening the damper after movement of the manually adjustable means closes the valve.

-3. In a control mechanism for regulating the supply of oil and air to a burner, a casing provlding an' oil supply chamber. a metering valve biased toward open position andcontrolling the flow of oil from the chamber, manually adjustable means limiting the degree ofA opening ofthe valve, a fan for supplying air to the burner, a damper biased toward position to close a natural. draft opening and controlling the natural draft and the ilowV of air discharged by the fan, and delay means including a leverage actuated by the manually. adjustable means for stopping the fan and opening the damper upon movement of the manually adjustable means for closing the valve and including an operating lever connected with the damper, a, lever for actuating the operating lever, and a yielding connection between the levers whereby movement of one lever may precede movement of the other lever to close the valve bev the burner from the fan; a leverage including a damper controlling the flow of air discharged by the-fan and the natural draft to the burner, and

delay means including a leverage 'actuatedby the manually adjustable means' for stopping the fan lever controlling movement of the switch, a lever actuating the damper and means interconnecting the two leversy for delaying movement 'of the switch until after movement of the damper, and adjustable means connecting the switch with the leveragewhereby the damper position is changed before the switch position is changed.

5. In a device for controlling the supply of oil and air to a burnerfcasing defining an oil supply chamber, a metering valve controlling the flow of oil from the chamber to the burner, an electric motor driven fan for supplying air to the burner, a switch controlling the circuit of the fan motor and closed by opening the valve, a heat motor including a bi-metallic element and aheater in the circuit to the motor and heated by the iiow of current thereto upon closure of the switch, a leverage actuated by the element for closing the valve to low fire position upon failure" of current ilow to the motor, and means for adjusting the action of the leverage.

6. In a system for controlling the flow of oil and air to a burner, a casing providing an oil supply chamben'a metering valve controlling the flow' 0L oil from the chamber, manually adjustable means for limiting the degree of opening of the valve, an electric motor driven fan for supplying air to the burner, a switch contrplling energization of the motor, a dampercontrolling the fiowof air to the burner by natural draft and from the fan, a leverage including a plurality of levers and a yieldable connection therebetween -i'or moving the damper` `into position to free a natural draftopeningvupon movement 'of the' manually adjustable means in the direction for closing-the valve, means connecting .fthe switch with the leverage for delaying opening of the switch until after opening of the damper, means to deenergization of the current responsive means forclosing the valve to low iire position.

able means for limiting the degree of opening of the valve, an electric motor driven fan for supplying air to the burner, a switch controlling enei'gization of the motor, means associated with the valve for closing the switch during the opening of the valve, a damper controlling the ilow of air tothe burner both bynatural draft and from the fan, a leverage for moving the damper into open position for the' ilow of natural draft upon movement of the manually adjustable means in the direction for closing the valve, an adjustable screw mounted in the leverage and acting on the movablecontact of the switch whereby opening oi' the switch is delayed until after opening of the damper, means responsive to the flow or current to the motor, and means responsive-to denergization of the current responsive means for closing the valve to low lire position.

8. In a system 'for controlling the ilow of oil and air to a burner, a casing providing the oil supply chamber, a metering valve controlling the flow of oil from, the chamber, manually adjustable means for limiting the degree of opening oi' the valve, an electric motor driven fan fo'r supplying air to the burner, a switch controlling energization of-the motor, means associated with the valve for closing the -switch during the opening of the valve, a damper controlling the ilow of air to the burner from the fan and by naturaP draft, a leverage for moving the damper into? open position for the natural draft upon movement of the manually adjustable means in the direction for closing the valve, means connecting the. switch with the leverage for delaying opening of the switch until after opening of the damper, a bi-metallic element in the circuit of the motor and heated by the flow of yelectric current thereto, and a leverage actuated` by-the element for closing the valve to low fire position upon failure of current flow to the motor.

9. In a system for controlling the ow of oil and air to a burner, a casing providing an oil supply chamber, a metering valve controlling the flow of oil from the chamber, manually adjustable means for determining the degree o! openingof the valve, an electric motor driven fan for :,svasss I 10. In a control system for the regulation of l oil and air supplied to a. burner. a casing providing an oil supply chambena metering valve controlling the ilow of oil from the chamber, an electric motor-driven fan for supplying air to the burner, a switch having its movable contact biased toward closed position and controlling the operation of the fan motor, a damper biased toward closed position and controlling the flow of air to the burnerfrom the fan and by natural draftfand a leverage including a plurality of levers and a time delay device and a yieldable invterconnection therebetween, the leverage connecting the switch an the damper and changing the damper position fore the switch position changeswhereby fan operation is commenced before the damper is closed to shut oif the natural draft and is continued until the damper is opened.

ll. In a control system for the regulation of oil and air suppligd to aburner, a casing providing an oil supply chamber, a metering valve controlling the flow of oil from the chamber, an electric motor-driven fan for supplying air to the burner, a switch controlling the operation of the fan motor, the movable contact of the switch being resiliently mounted, means biasing the movable switch contact toward closed position, a damper biased toward position to shut oif natu-l ral draft and controlling the flow of air to the burner both by the natural draftand from the fan, a leverage connecting the damper and the switch for changing the position .thereof and insupplying air to the burner, a switch controlling energization of the motor, a da-mper controlling the flow of air to' the burner both by natural draft and from the f an, a leverage including a plurality of levers and a yieldable connection therebetween for moving the damper into open position for the natural draft upon movement of the manually adjustable means inthe direction for opening the valve, an adjustable means mounted in the leverage and acting on the movable contact of the switch whereby opening of the switch is delayed until after opening of the damper, a bi-metallic element in the circuit of the motor and heated by the ilow of electric current thereto, and a leverage actuated by the element for closing the valve to low re position upon current failure to the motor.

cluding a lever controlling movement of the switch, a lever actuating the damper, a dash-pot acting on the damper-actuatin lever and a yieldable interconnection between he levers, and adjustable means mounted on the switch controlled lever and bearing on the movable contact mounting oi' the switch to stress the mounting upon movement of the leverage whereby a natural draft opening is closed by the damper after starting of the fan and is opened before stopping of the fan.

l2. In a system for controlling the flow of oil and air to a burner, a casing providing an oil supsply chamber, a metering valve controlling the flow of oil from the chamber, manually adjustable means for limiting the degree of opening of the valve, an electric motor-driven fan for supplying air to the burner, a switch controlling energization' of the motor, a damper controlling the flow of air to the burner from the fan and by natural draft, a leverage for moving the damper into open position for the flow of natural draft upon movement of the manually adjustable means in the direction for closing the valve, means connecting the switch with the leverage for delaying opening of the switch until after openingof the damper for natural draft, means responsive to the flow of current to the motor upon closure of the switch, closure of the switch opening the valve to high ilre position, and means responsive to deenergization of the current responsive means for closing the valve to low nre position.

ROY W. JOHNSON. 

